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Considerations for managing a horse with heaves provided

by Wyoming Livestock Roundup

Some horses suffer impaired respiratory function due to congestion and constriction of the airways, similar to a person with asthma. This condition is generally the result of breathing dust containing mold particles or pollens – often due to the conditions in which horses are fed and kept.  

Horses are super athletes, primarily because they have sizable lung capacity for keeping blood and muscles well supplied with oxygen during strenuous activity.  Anything interfering with proper working of the lungs and air passages can limit a horse’s athletic ability. If a horse tends to suffer bouts of impaired lung function, the environment and management of the horse needs some changes. 

Environmental treatments 

Large Animal Internal Medicine Veterinarian Amy Johnson says the most important treatment is simply environmental and dietary management changes to reduce the horse’s exposure to the triggers for this disease.  

 “The triggers are usually dust, molds and endotoxins found in hay and straw in a barn environment,” she explained. “We tell owners the ideal situation is to have the horse out on pasture 24/7. If this is not possible, the horse should be in a stall with the least exposure to dust particles in the air the horse is breathing.” 

A corner stall by a window might be better than a stall in the middle of the barn.  

Johnson advised, “Make sure the most air flow is away from any storage stall or area where bales of straw or hay might be located. The worst barns are the ones with an overhead hayloft, where particles rain down from the ceiling.”  

Barn stalls adjacent to an indoor arena will also be dusty if they share the same air space.   

“When horses are exercised, they churn up dust,” Johnson noted. “If the horse with heaves must be in a barn, it should be one with minimal dust.” 

She continued, “If the horse has to be in a barn part of the day, it is important to not have the horse in the barn when stalls are being cleaned or people are blowing or sweeping the aisles. Even if the other horses are in the barn while it’s being cleaned, make sure the horses suffering from heaves are not.”  

“Regarding bedding, straw is probably the worst choice,” Johnson shared. “It pays to try to find a low-dust bedding. We use chopped paper or cardboard bedding at our hospital for these horses.”  

She explained sawdust is also better than straw.  

“Some people wet down the fresh bedding a little to reduce the dust before they put the horse back into the stall,” Johnson added. “Pellets over stall mats also work pretty well for a low-dust bedding.” 

Feeding considerations 

“If the horse is outside and being fed hay, make sure to not feed from big round bales,” Johnson said, noting those have higher levels of endotoxin, dust and mold compared to other forage sources. “People think the horse will be fine just because it is outside on pasture and then wonder why the horse isn’t getting better. This is because the horse is sticking its nose into a round bale and breathing dust.”  

Feeding is an important issue, especially paying attention to dust levels in feed.   

“It’s really a spectrum,” Johnson said. “Some of the mildly affected horses – as long as they are outside – can tolerate hay. Other horses may not be able to tolerate dry hay, unless the hay can be dampened to reduce the amount of inhalants.” 

She continued, “A few, however, still inhale enough particles and allergens from wet hay to trigger the disease, and have to be taken off hay. They should be fed a complete pelleted ration or cubes instead of hay.”   

In severe cases it also helps to moisten the cubes or pellets. 

Heaves medication 

If a horse suffers an episode of heaves and has trouble breathing, medication is necessary to reduce the inflammation and bring the horse back to a comfort level where they aren’t struggling to breathe.  

 “Medications we usually recommend for an acute crisis would be systemic steroids, such as dexamethasone or prednisolone, administered either intravenous or in the muscle, or even orally and through bronchodilators,” said Johnson.    

This disease involves both inflammation and constriction of the airways.  

“Horse owners need to get rid of the inflammation with steroids and then treat with a bronchodilator to open the air passages that are squeezed shut,” Johnson explained. “Probably the best course is to use one of the aerosolized bronchodilators, such as an inhaler as they seem to work more quickly than oral medication such as clenbuterol, which is marketed as ventipulmin.”    

“An aerosolized bronchodilator has been shown to improve lung function significantly within about five minutes, and the oral drugs can’t act that quickly,” she added.    

“In the long term, if horse owners have a horse needing more than just environmental changes, it is suggested to use an aerosolized medication as a maintenance therapy,” said Johnson.  

This reduces the systemic side effects which can be a problem when keeping a horse on a systemic steroid. She noted though, there are several options including the Flexineb and Equinehaler to give the horse aerosolized medications. 

“This involves a big up-front cost because these are not cheap, but in the long term, the horses benefit enough to make it worthwhile if the owner can medicate the horse,” Johnson shared. “Most horses tolerate these devices pretty well, but once in a while, we find one that wants nothing to do with it.”   

Owners have to figure out what works and what is workable for each individual horse. 

Lifelong condition 

“Owners need to understand from the beginning this is not a treatable condition and it goes away and never have to think about it again – this is a lifelong problem. The horse may be useful and continue a performance career for many years, but will not be able to go back to the management situation or conditions in which it started showing signs.”  

The owner must continue with the environmental changes and altered management to keep the horse breathing normally. 

“There are many horses with no clinical signs once they get out on pasture and away from the dust of a barn and hay,” Johnson said. “They are fine as long as they stay away from allergens in the hay and dust.” 

She continued, “As far as diseases go, this one is fairly easy to deal with because even though we don’t yet fully understand everything about why heaves appears, the treatment and management protocols have been fairly well established.” 

Heather Smith Thomas is a corresponding writer for the Wyoming Livestock Roundup. Send comments on this article to  

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